1. Yes. I think this is the case even on the wider models, e.g. Hawk, but I am not sure.
2. So far I am happy with how I installed the holders, they are solid and should hold up over time.
3. The Stebel horn was an impulse buy, and I always like having a project. It is way louder than the stock horn, people know when I am honking at them, and I like that. I would do it again.